Speech privacy apparatus



j 3l i950 H. P. HUTCHINSON SPEECH PRIVACY APPARATUS 2 sheets-sheet 1Filed Jan. 7, 1945 Jan. 3i, 1950 H. P. HUTcHlNsoN SPEECH PRIVACYAPPARATUS 2 Sheets-Sheet 2 Filed Jan. '7, 1943 Patented Jan. 31, 1950NITED STATES PATENT vOFFICE 2,495,727 SPEECH PRIVACY APPARATUS HenryParks Hutchinson, Washington, D. C.' I Application January 7, 1943,Serial No. 471,580

(C1. 17o- 1.5)V

(Granted under the act of-March,3, 1883, as amended April 30, 1928; 3700. VGr. 757) 7 Claims.

The invention described herein may be manufactured and used by or forthe Goverment for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates to means for maintaining secrecy ofcommunications, particularly in telephone circuits.

More specifically my invention comprises a communication net-Workincluding at least two stations, one distant and one local, each of saidstations having a telephone, a pair of adjustable oscillators arrangedso as to be alternately connected to a circuit including said telephoneand adapted, when so connected, to modulate the ow of electricitythrough said circuit at varying frequencies and thus to vary thechannels through which communication takes place, and a cipheringmachine havingr a variable cycle of operation, the variations of saidmachine occurring in a pre-determined sequence of a great number ofcycles without repetition, said ciphering machine being connected sothat, at each cycle of its operation, one oscillator is connected to thetelephone circuit and the other is disconnected therefrom, and thedisconnected or idle oscillator is adjusted in accordance with thevariations of said ciphering machine so as to select the next channelthrough which communication takes place.

An object of my invention, therefore, is to provide a communicationsystem having a plurality o of adjustable selecting vdevices such as theoscillators referred to above. Since one of these selecting devices isidle while the other is operating, the idle or disconnected device maybe adjusted to select the channel or frequency at which the device willoperate when next connected into circuit. Moreover, this adjustment orselection need not be simultaneous at each station but must only becompleted before the next cycle of operation takes place and the deviceis connected into circuit.

It is a further object of my invention to provide at each station insuch a communication system, a switch for determining which selectingdevice is to be operative. The actuation of these switches can vary atrifle from exact synchronism since the operatveness of my device doesnot require that the sending and receiving stations be exactlysynchronized but merely that the oscillators be adjusted tothe samefrequency and therefore operating through the same channel.

Yet another object of my invention is the provision of a local source ofpower, such as a battery, at each station so that the operation of 4theciphering machine to select the channel next .to become/operative isindependent at each station. i

VStill an additional object of my invention is the provision of acommunication system employing wire. circuits connecting the variousstations and having oscillators of sucha type that the :impulse whichinitiatesany. cycle of operations cannot be interrupted by anunauthorized person without a direct connection to the wire circuit. f

, Continuing the objects of this invention, there is afforded meanswhereby'any cycle can be caused to commence either (a)'From one stationv(b) alternately from either end of the line.

For a further exposition of my invention, reference may be had to theannexed drawings and specification at the-end whereof the novel featuresof my device will be specically pointed out and claimed.

In the drawings,

Fig. 1 is a block diagram outlining the communication system includingboth local and distant stations.

Fig. 2 is a diagrammatic and schematic view of the selector shown as 'ablock in Fig. 1 and forming a part of one of the stations.

Fig. 3 is a diagram showing by means of blocks and circuit connections,the tone ringer shown as a block in Fig. 1.

Fig. 4 is a representation showing a comparison between electricalimpulses of varying duration.

In that embodiment of my invention selected from among others forillustration in the drawings and description in the specification, mydevice is shown as follows:

Y In the drawing and specication, like parts are denominated by likeletters of reference, the parts at the distant station beingdistinguished by the same reference character with the addition of theletter d. y

Block diagram, Fig. 1

M. Selector 1 also has line terminals L1, La which are connected byconductors to the terminals ILi, 2L2 of the tone ringer generallyindicated at 9, as is shown in greater detail in Figs. 2 and 3,respectively. Tone ringer 9 is connected through low-pass filter F2 tothe output side of a high-pass lter F3 which is also. connected to theoutput of'modulator M. The combined output of filters F2 and F3 is fedthrough a wire or radio link forming a communication channel to one ormore distant stations.

Selector, Fig. 2

This figure is a diagram in which the plus terminal of battery II is atthe top of' the sheet and the minus terminal is at the bottomi Y A motorI2 operating through clutch I3 supplies the power to operate aciphering; or cryptographic machine (C) practically identical with thosedisclosed in U. S. Patents Nos. 2,089,603 and 2,247,170

to. Hagelin. This machine C includes a detent.

cam D which is held against movement in. one. direction by positioningcam. I5 and, in the` other direction, by/ av latch generally indicated'at L` and having a portion I.'I. cooperating with. ca m. El Latch L ismounted. under the. control of the armature. of.: relay- R3. Latch LalsoV has a. por-v tion` I8 which, when cam. D is` in. a lockingposition, prevents operation. offa starwheel When cam D does not lockstar wheel W, star wheel W is turned bythemotor I2 acting through thecryptographic, or cipheringelements C and thus causing operation ofswitch C3. Motor- I2 also actuates, through detent. D. and, ciphering`machine C, cam, W2 controlling, the` operation of switch C4. Y

StartingswitchzKZis connected inr parallel with switchY C4' and, inseries with this' parallel arrangement, is connected av multi-contact-`switch. RIA having a movable: contact 20. and. a pairv of banks ofstationary contacts 2|A andl 22. Manually operable switches Ko andKe-cooperatewith banks 2Il andi 22V, respectively. In, series withswitches: Ko and; Ke is connected'l a parallel arrangement consisting ofthe coil of relay R2 and line-` terminal L2. Relay R22 has a: delaywinding IlIsLthereon. An adjustable resistanceXR is cone nected inseriesv withwinding-LH. Relay R2 has an. armature `which operatesswitchl C21 connected in: seriesfwith` the coil oi relay R3. Relay R2also operates switch CI which is connected inv parallel with a circuit'.containing a manually-operable switchKI I Ill and acam-operatedstoppingswitch CSIS, these parallel circuits being connected in series. with thecoil of. relay. RI'. Connected in series. with amanuallyeoperable..switch. KI are the coils of relays R4 andR5 andcam-.operated stepping switches CS2 and C53"` whichV are. connected; inparalleli with; eachV otherand in series with manually operated; switchKI LI. Manually operatedV switch K pII isl connected; in. series with.the movable contact 24 of multi-ccntactswitch RIB having a pair of banksofV` stationary contacts 25 and 25 which are respectively connected to:the coils-off relays Rdand R5; Relays R4 and R5r operatepawls 21 and 29Awhich rota-tev selecting switches- 28 andl 30 respectively which, intur-11,. contact with stationary contacts. 32 andA 3'4 which'are eachconnectedto a bank of stationary contacts. 367i orl 38 of;multi-contact. swit'clry RIC whichL has a. movable-contact? 39; fromwhichY the output. current. fm. is. led. Y Switchesl', 32, and- 305.34.. each select a desiredf outputirequency.` of oscillator All. or 42'respectively'. Cams 4t', dlandE` itil-:operate switches` CS1; CS2 andiC53, respec-` tively. Relay RI has an armature in the form of a pawl 5)which rotates ratchet 52. Movable contact 2E), cam 4d., ratchet 52 andmovable contacts 24 and 39 are all mounted on shaft 54 so as to besimultaneously operated by relay RI. Cams 46 and A8 are respectivelymounted on shafts 'i` and 5,8 of switchesI 28` and 3.o and serve tooperatesteppingswitches GSS4 and CS2. Shafts 54, 56, and 58 togetherwith shaft '65, which drives clutch I3, detent cam D, and cam W2, arerepresented on the, drawing by dotted lines. Switches KI, KI I, KI IIand KI I l I are ganged together by means ofa connector 59 shown indotted lines. The gangingv or interlock between these switches is suchthat Kil' is always in the opposite position from:Y switches KI, KIIIand KIIII. The selectors also include line terminals LI, L2, a, b, and cwhich areconnected by a cable to the correspondinglyi marked` terminalsof the tone ringer next to be described.

Tone.. ringer. Fig... 3'

The tonerinsenf is generally indicated at. 9 and. comprises a manuallyoperable nendcekfingf sigg-- maling.: key; Kei which-.Cannole 12a-irs;of. contacts 63 and 6s.: connected to. tone oscillator. t and-V Conenected, respectively, in parallel with.pairs.4 of contacts. 55; and'.6,6;- under the, control of; the. coil of relay Rtgwhich alSQi controlscontacts; 51.- in series, with the colla otrelayfftl and amnlinendetector. 3.8i. Relay Rlactuates; contacts 69,. 119, and. 1,-I whichlast; are;l in the: circuit.. ot. a. Signal indleatorA suoli asf. a..lamp.. bell or thelike.. It Wire circuits; permitting' direct. current,signalingarey used be.- tweerr. the Various Sta-.tions then the tone;oscila4 latormay: be. replaced by' a linef battery andtheampliendetector elilnciinated.r

Thiais.. a diagram in whichL the. abscissa rep-y resents, timemilliseconds, the time at which` onev selecting 0r initiatilfls pulse.occurs. beltsy show nat, P andthe. timefatwhicnthe. next .selec,t. ing`or. initiatingl pulse being. shown; at PI. The. blocks-f are,-Vproportonalto thev time. required for, the, variousy selectors labeledSel.v d,1 Sel. (dh. and Sel. (11) tol operateto adjust the idle, Or.-dise cgnnectedf' oscillators-sofas to be ready to modu late. thelvoicecurrents; ata few,l frequency. when next. the oscillator isconnectedinto circuit.

@partition- In. order to receivecommunications ateachstaftion, thecipheringV devicefCis, adjustedy according?` to; a predetermined,alfeelrient` so. that each. der vice actuatesswtch. C3. andthemechanisms con.- trolled therebyasimilar. varying amount ateach.cy,cle.off operation of; the, device. In other, words, at. each4cycletarf Wheel. @loses Switch. G3i the; same or aidiferent number' of;timessothat the, mechanisms controlled by svvitcli,` are-.stepped acorresponding, number. of. times and! a diierent channel; selected..variations oi,Y the cipher-1 ins: riltmhi,nel oecue inf. a: need: orpredetermined: sequence or seresldependinsi unontheiadi ust-ment. i-thecipherinefdevicabut this sequence on series does` not: repeat. itseltfexcept. atten' such; a; large number.-

cycles-V as; could: only; be.l expressed by) an; a.strnriomic.alYnumberz. means; by which:` adiustmentofthe cipheringmachineeismade-.andi the. mode ofl oper-ation. thereoff are. set forth. im theHagelin. patents. above referred tot..

To insure that, each; station; ofi the: communi.I cationnetwork is. inproper conditionL to Yreceive communicationscven-theichannel: initiallyselecte d and-rito continue to change' StoA each! 'channel as itisselected, switches KIl and KI I I and Ki-I'LI are closed and switch KHis opened. *This-connects the coils of relays RI, R4 andr R5 acrosstheterminals of battery Il under the respective control of steppingswitches CSI, CSS; and CS2. The energization of its coil causesrelayRIieto turn shaft 54 until movable contacts 2li, .24,and 39are inthe proper initial position resting upon the desired cooperatingstationary icontactsrat which time cam 44 opens switch CSILand stopsfurther movement. Likewise,.energizationlof the coils of relays R4 andR5 causes these coilsto turn switches 28, 32, and 3U, 34,respectivelyfand thus adjust the oscillators and 42 untila desiredchannel is connected from. that oscillator which is connected intocircuit. Then .camss .and 48 open switches CSS and CS2, respectively.When the movable contacts 2U, ,24,.and 39, and oscillators 4I) and 42have all been movedy into the desired position so thatA their elementsoccupy the same position at each station, the networkis Ain condition tobegin operations. Switches KI, KI I I and KI I I i are then opened andswitch KI I Kis closed.

The operator closes switch K2 which closesra circuit through movableswitch contact .20,A which may be assumed to be in engagement with acontact of bank 2i and switch Ko, which maytbe assumed to be closed,thus energizing theLcoil of relay R2 and transmitting a pulse over therline whose terminals are LI, L2. This causes `relay R2 to vcloseswitches CI and C2.- Closure of switch Cl energizes the coil of relayRlfcausing pawl 59 to rotate ratchet 52 and, consequentfly, shaft 54 andmovable contacts 20, 24andV 3,9 mounted thereon, one step. This movementAof contact 2G opens circuit with stationary contact bank 2I thuslie-energizing the coil of/relay VR2. Movement of contact 24 out ofengagement with stationary contact bank 26 and intoengagement withstationary contact bank 25 shifts-the` e951 of relay R5 out of circuitand the coil of relay R4 into. circuit. So also the operation of switchRIC disconnects the output from oscillator 42 from the circuit andconnects the output from oscillator 4I] into circuit.

Simultaneously, switch C2 is closed, which connects the coil of relay R3into circuit so that latch Lhas portion I'I withdrawn from dii-179m; camD and part i8 withdrawn from starwheel W. Motor l2 turns shaft 60whereby starwheel W is rotated an amount depending upon the adjustmentof the ciphering device. Thisrota- 'tion causes switch C3 to be closed anumber tof times depending upon the amount of rotation of star wheel W.Thus a circuit is closed through switch C3, the coil of either relay R4or R5 (depending upon whether movable contact 241s in engagement withstationary contact bank $25 or 26) and switch KII.

Referring now to Figs. l, 2, and 3, whilethe above mentioned events havebeen occurring. energy has been applied through the line havingterminals LI, L2 to. the tone ringer 9 at the same station. Such a toneringer is shown in Fig. 3. This energy enters tone ringer 9 throughcontacts ILI, 2L2 and energizes the coil of relay R5 which also has anarmature which operates switch contacts t5, 55 closing circuit throughtone oscillator 6I and transmitting a pulse through low-pass lter F2over the wire or radio link to the distant station or stations of thenetwork. At such distant station such a pulse passes through low-passlter F2 (d) to the tone flRlay R6 .isfa Quick acting relaytvliil, T iieto'winding L'Ili ahdits ',assciated, adjust l resistor XR,"'rela'y R2`is; a' `delayed-acting`relay, Because of this, when the coils of'both1these relays' are energized simultaneously, relay V4lti has anopportunity to transmit a pulse to the distant selector 'I' (LDQand toYcause it to step before local lrelay R2 operates and breaks cir.'-

Icuit byshifting movablecontact 20 into engage ment with a yContact ofstationarycontactbank 22. ft 'rc Duringeach cycle .otfA-l operation,after `'star wheel W has completed itsmovement and vacl- .justedthe idleoscillator, cam W2-comes into loperation and closes switch C4, which isconnected in parallel with starting switch K2. Since movable switchYcontactlll has moved out of engagement -vvith a contact of bank 2l andinto .engagement with a contact of -bank 22, no action takes place ifswitch Ke is Jopen. If,rhowever, sWitchKe-is-elosed,-the coil of relayR2 is en ergizedgand the next cycle of operations similar to the initialycycle is commenced. Thus it will be seen that a .cycle of operation canonly. be initiated at that station at which the movable contactisinengagement with a contact of that bank of stationary contacts 2l or 22in .series with which the corresponding switch Ke or Kois closed. Inother words, if both switches Igoeahd -K e arefclosed atvone station,the com munication-channels can only be shifted from k,that'enci but ifswitch Kois closed at the local station and switch Ke (d) is closed atthe distant stationmthe `initiating impulses originate from .the twostations alternately.

I claim: 1L-,Meansfor maintaining secrecy of telephone :conversationscomprising' a source of power, Aat least one .local and one distantstation, each of said stations `including a telephone, a pair ofoscillators each adapted to modulate theiiow of electricity to and. fromsaid telephone at a number olf'diiierent frequencies, a switchconnecting said telephone under the control of one or the other of saidoscillators, a pair of motors each 'connected to :one of saidoscillators so as to adjust the same to any one of a number of desiredfrequencies, a second switch connecting one or other of said motorsacross said source of power, and a ciphering machine having a varyingcycle of operations, said variations occurring in a predeterminedsequence of a great number of cycles of operation without repeating,said machine being connected so as to operate said switches to shift theconnection to said telephone from one oscillator to the other and toconnect the motor controlling the disconnected oscillator under the'control of said machine.

2. In a system of the nature described, a communication apparatus, aplurality of com munication channels fed by said apparatus, oscillatorconnected into each of said channels., a switch between said apparatusand said os lators for selectively connecting saidapparatus and one ofsaid oscillators while disconnecting said apparatus from the other ofsaid oscillators, a translating device associated with. each of saidoscillators for selecting a channel controlled by said switch, a sourceofpower for said translating devices, means for controlling theoperation of said translating devices said lastvnentionedrmeansproviding an unpredictable sequence of controlling impulses, and asecond switch between said last-mentioned means and said translatingdevices arranged to disconnect said means from an operative translatingdevice and to connect the same to an inoperative trans lating device.

3. In an apparatus of the nature described, a local station and adistant station each of said stations comprising a communicationequipment embodying variable means for selecting a com municationchannel from among a plurality of channels each of said variable meansbeing driven by a motor the said'motors being connected by a switchpermitting operation of but one motor at a time, means for determiningthe amount of motion of said motors last-men tioned means being in thenature ci a key erator providing an unpredictable motor actuatingimpulses, a switch operate-:l periodically by said last-mentioned meansto stop the same said last-mentioned switch a plurality of stationarycontacts, and a plurality of further switches cooperating therewith andwith the other station for dcterm ng the stau tion from which saidlast-mentioned may be controlled. Y

4. in a system for privately transmitting information, the combinationo' a pair of communication apparatuses between which com municatio-n mayestablished over a plurality of channels each apparatus including pluralmeans each supplying a plura y ci; different iiXed carrier frequenciesand a switch for selectively connecting said means said channels, forswitching from one channel to another for communication purposesaccording to an une predictable and means for switching another carrierfrequency to a channel before selection thereof for communication.

5. Means for maintaining secrecy ci telephone conversations, comprisinga source of power, at least one local and one distant station each ofsaid stations including' a telephone, a pbwality of oscillators Veachadapted to modulate iiow of electricity to and from said telephone at anumber of different frequencies, a switch connecting said telephoneunder the control of one or another of said oscillators, means foradjusting each of said oscillators to any one of a number of desiredfrequencies, a Second switch connecting said lastMmentioned means acrosssaid source of power, and means for operating said switches inaccordance with an unpredictable rule to shift the connection to saidtelephone from one oscillator to another and to vary the frequency ofthe disconnected oscillator.

6. In a system for private communication, the combination of at leasttwo stations, a plurality of communication channels extending betweensaidstations, a channel selector at each of said stations each selectorcomprising a plurality of contacts arranged in gr ups equal in number tothe said communication channels said contacts being arranged in an ordernot related to their grouping and adapted to have contact made therewithby a cooperating switch member, means for driving switch members inaccordance with an unpred table rule, and means including interlockingswitch controlled circuits between said stations for determining thestation from which said di" ng for said switch in? bers are actuated.

7. in a system private communication, the on of at least two stations, aplurality combinati oi corr nicaticn channels extending between saidstations, c annel s lector at cach of said HENRY PARKS HUTCHINSON.

REFERENCES CITED The following references are of record in the fileV ofthis patent:

UNITED STATES PATENTS Number Name Date 1,571,005 Hartley Jan. 25, 19261,573,924 Fletcher Feb. 23, 1926 1,366,651 -L icing npr. i7, 19281,709,901 Espenschied et al. 23, 1929 v 1,?25556 Chestnut Aug. 20. i9291,75%:,181 Espenchied May 6, 1930 `1,8l6,53 Bo-wn Aug. lll 2,290,559Mitchell May le, 1940 2,204,050 Purington .lune il, 1940 2,213,320Mathes Sept. El, V1940 2,301,22 Mitcl'iell Nov. lo, 1942 2,402,059 CraibJune l1, 2545

